Exploring brainstem function in multiple sclerosis

In this study the researchers examined whether the diagnostic sensitivity of clinical examination, evoked potentials (EPs) and magnetic resonance imaging (MRI) can be improved by adding the assessment of vestibulo-masseteric (VMR), acoustic-masseteric (AMR), vestibulo-collic (VCR) and trigemino-collic (TCR) reflexes.

Sixty patients with relapsing remitting MS were selected. Patients underwent clinical, neurophysiological and MRI evaluation within two weeks. Controls underwent clinical examination and recording of brainstem reflexes (BSRs). Neurological status was quantified with the EDSS and Kurtzke’s functional system (FS) scores. MRI scans were acquired with a 1.5 T Superconducting system. Global and regional FLAIR, T2, STIR, T1 and T1-gadolinium enhancing lesion load was evaluated, with a semiquantitative method, both for supratentorial-cerebellar compartments and brainstem. Multimodal EPs of the visual (VEPs), brainstem auditory (BAEPs) and somatosensory (median nerve stimulation: mSEPs; tibial nerve stimulation: tSEPs) pathways were recorded. BSR evaluation consisted in recording VMR and AMR from masseter muscles and VCR and TCR from sternocleidomastoid muscles.

The results indicate that the paired use of the BSR/EP batteries is associated to a detection accuracy of brainstem dysfunction, with significantly higher sensitivity than that achieved by clinical and MRI procedures taken together.

This finding supports previous findings of discrepancies between neurophysiological data and both clinical and MRI evidence. Demyelinating lesions can exist below the threshold for detection in clinical examination and conventional MRI. This occurrence underlines the value of such tests in detecting silent lesions. Conversely, subtle lesions appearing in the MRI or producing clinical evidence of brainstem involvement, but localized in brain areas non-critical for the generation and/or synaptic transmission of the electric signal, are sometimes insufficient to produce conduction neurophysiological abnormalities.

: Magnano I, Pes GM.
Source: Clin Neurophysiol. 2014 Mar 25. pii: S1388-2457(14)00166-7. doi: 10.1016/j.clinph.2014.03.016. [Epub ahead of print]
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